1. Field of the Invention
The present invention relates to an inkjet recording head and image formation apparatus, and more particularly to a structure of a recording head suitable for preventing a discharge defects due to ink drying inside nozzles and an image formation apparatus using the recording head.
2. Description of the Related Art
Inkjet-type image formation apparatuses (inkjet recording apparatuses) attach ink droplets on a recording medium such as recording paper by discharging ink from nozzles provided to a recording head in accordance with a print signal while moving the recording medium relative to the recording head, and an image is formed on the printing medium by ink dots.
In these inkjet recording apparatuses, when the nozzles for discharging ink droplets are exposed to the atmosphere and meniscus (i.e. the boundary between the ink and the outside air) is left exposed for a long period of time, the viscosity of the ink inside the nozzles increases due to drying, and this causes discharge defects. It is for this reason that the print head ink is normally covered with a cap after printing to prevent the meniscus from drying out.
Disclosed as a separate technique in Japanese Patent Application Publication No. 9-1814 is an inkjet recording apparatus having a viscous material supply unit for delivering a viscous material that prevents the ink discharge surface from drying, and also having a viscous material removal unit for removing the delivered viscous material from the print head surface. In accordance with this publication, there is disclosed a structure whereby a viscous material is delivered to a discharge port by fitting a cap loaded with viscous material over the nozzle surface (ink discharge port surface) of the print head, and there is also disclosed a structure whereby the viscous material on the discharge surface is wiped away by relatively sliding a blade composed of rubber or another elastic material on the discharge port surface. The viscous material is preferably one having moisture retention or moistening properties, and glycerin and ethylene glycol are exemplified as viscous materials that are suitable in the case of water-based ink.
Disclosed in Japanese Patent Application Publication No. 2001-71520 is an inkjet printer provided with a sliding contact member that cleans as it slidably rubs against the discharge surface, applies a coating film material on the discharge surface, and forms a barrier film on the nozzles. Silicone oil is exemplified as the coating film material, and the sliding contact member has a structure in which a wiping layer for cleaning and a coating layer for applying the coating film material are laminated.
However, the structures proposed in the prior art use a large quantity of sealing liquid in order to apply the viscous material or the coating film material (hereinafter these are generically referred to as “sealing liquid”) over the entire surface of the ink discharge surface of the print head. The ink discharge surface of the print head is treated with a liquid repellent (water repellent) that repels ink, so it is also not a simple matter to apply the sealing liquid.